The equipment we are applying for would provide rapidly switchable attenuated and properly filtered light for wide field epifluorescence, microscopy in an environmental chamber to preserve integrity of cultures, high speed low noise detection, off-line storage and processing of large datasets, deconvolution software to improve spatial resolution, and image analysis. The users assembled in this application share a common need and interest in imaging dynamics of proteins (or nucleic acids) at high temporal and spatial resolution in live cell cultures. This type of imaging cannot be done at AECOM currently forcing projects that require this capability to acquire the data by more indirect and problematic approaches. We demonstrate that new high speed and lower noise instrumentation currently available obviates technical problems associated with these projects and will allow the user group to advance their research more rapidly and with fewer artifacts. The users? projects are varied and involve the visualization of roles of P1 4-kinases in lysosomal enzyme sorting (Backer); vesicular trafficking in hepatocytes and oligodenrocytes (Wolkoff and Larocca); regulation of meiotic recombination (Cohen); roles of cofilin and L1M-kinase in actin nucleation (Condeelis); and mechanisms of HIV-1 replication (Kalpana). All projects require the capability to image cells or in vitro assay systems at high spatial resolution with minimum exposure to light or at high speeds.